"The fragments we found don't belong to any group registered on the continent before, which indicates a greater diversity of the plesiosaurs in Antarctica than previously suspected," said team leader Alexander Kellner, of the National Museum of Brazil at the Federal University of Rio de Janeiro.

Fragments of the vertebrae, head, and flippers suggest the newfound plesiosaur was 20 to 23 feet (6 to 7 meters) long. The bones weren't, however, enough to identify the species of the plesiosaur.

Plesiosaurs roamed the seas worldwide between about 205 million to 65 million years ago, reaching the Southern Hemisphere by the mid-Jurassic. The animals had a range of different sizes and features, but mostly shared small heads, long necks, and big bodies. (See a prehistoric time line.)

"If the Loch Ness monster ever existed, this would be its best representation," Kellner said.